I disagree with my pediatrician

We went for our 2 week check up today. My baby is 3 weeks old tomorrow but was in the NICU so we're catching up on the regular doctor appointments. They weighed him and he's gained a whole pound since birth, they were very happy with that since he was a 34 weeker.

The doctor asked how much he's been eating. I told her the past few days he's been eating almost every hour and a half to 2 hrs. I figured he was going through the 2week growth spurt, and was cluster feeding. She agreed, and then told me I really should be trying to space him out to 4 hours because feeding that often isn't "sustainable". She told me to put him in his bouncer and try to distract him while he's crying.

I was told by the lactation consultant at the hospital that I should be feeding on demand, and that some days all baby will want to do is eat and that's normal. I agree with the lactation consultant. He's gaining great weight, I know he's getting enough food. I don't get why the doctor would tell me it's not sustainable?? I cant imagine letting a newborn scream for 3 hours because theyre hungry is a good idea right??